GO:0047613 aconitate decarboxylase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0047613 (aconitate decarboxylase activity) catalyzes the reaction cis-aconitate + H+ = CO2 + itaconate, the committed step in itaconate biosynthesis.
• The enzyme responsible is encoded by ACOD1 (also known as IRG1), an immunometabolic gene strongly induced in macrophages and neutrophils during infection and inflammation.
• Itaconate produced by this activity has anti-inflammatory and antimicrobial effects, including inhibition of succinate dehydrogenase and activation of Nrf2.
• ACOD1/itaconate is implicated in sepsis, atherosclerosis, arthritis, cytokine storm, and cancer metastasis, making it a therapeutic target.
• Studying this activity requires integrating metabolic assays, CRISPR knockout/knock-in models, and transcriptomic or proteomic readouts.
• EDITGENE provides CRISPR cell model services (KO, point mutation, knock-in, overexpression) and library screening to dissect ACOD1 biology.
Description
Aconitate decarboxylase activity (GO:0047613) is a molecular function that converts cis-aconitate into itaconate and carbon dioxide. This reaction is the defining catalytic step in the production of itaconate, a metabolite with broad immunomodulatory and antimicrobial properties. The enzyme responsible, ACOD1 (also called IRG1), is highly induced in myeloid cells upon Toll-like receptor stimulation or infection, linking this activity directly to host defense and inflammation. Because itaconate influences macrophage polarization, cytokine production, and metabolic reprogramming, aconitate decarboxylase activity has become a focal point in immunometabolism research. The importance of GO:0047613 extends beyond basic enzymology. Genetic and pharmacological studies have shown that ACOD1-derived itaconate suppresses inflammatory responses and protects against tissue damage in models of sepsis, atherosclerosis, and arthritis. In cancer, ACOD1 expression in neutrophils has been linked to resistance to ferroptosis and promotion of breast cancer metastasis. These findings position aconitate decarboxylase activity as a node connecting metabolism, immunity, and disease. For researchers, understanding GO:0047613 requires knowledge of its catalytic mechanism, regulation, and the cellular contexts in which it operates. This article synthesizes current evidence from QuickGO and peer-reviewed literature to provide a research-grade overview of aconitate decarboxylase activity, its key genes, disease relevance, and experimental strategies for studying it.
aconitate decarboxylase activity At A Glance
| GO ID | GO:0047613 |
|---|---|
| GO term | aconitate decarboxylase activity |
| Ontology | molecular_function |
| Synonym | CAD activity; cis-aconitate carboxy-lyase activity; cis-aconitate carboxy-lyase (itaconate-forming); cis-aconitic decarboxylase activity |
| Major function | Catalysis of cis-aconitate + H+ = CO2 + itaconate |
| Enzyme class | Carboxy-lyase (decarboxylase) |
| Substrate | cis-aconitate |
| Products | itaconate and carbon dioxide |
| Representative gene | ACOD1 (IRG1) |
| Cellular context | Mitochondria-associated in activated macrophages and neutrophils |
What Is GO:0047613?
According to the Gene Ontology, aconitate decarboxylase activity (GO:0047613) is defined as the catalysis of the reaction: cis-aconitate + H+ = CO2 + itaconate. In other words, this molecular function removes a carboxyl group from cis-aconitate, releasing carbon dioxide and producing itaconate. The term is synonymous with CAD activity, cis-aconitate carboxy-lyase activity, cis-aconitate carboxy-lyase (itaconate-forming), and cis-aconitic decarboxylase activity. It is classified under the molecular_function aspect of the Gene Ontology and represents the enzymatic step that commits cis-aconitate to itaconate biosynthesis.
Why Is aconitate decarboxylase activity Important in Cell Biology?
Aconitate decarboxylase activity is important because it produces itaconate, a metabolite that modulates immune responses, microbial growth, and cellular metabolism. This activity is a key effector of immunometabolism, influencing outcomes in infectious and inflammatory diseases. Understanding GO:0047613 provides mechanistic insight into how cells reprogram metabolism during inflammation and offers potential therapeutic targets for conditions such as sepsis, atherosclerosis, and cancer.
• Produces itaconate, an anti-inflammatory metabolite that inhibits succinate dehydrogenase and activates Nrf2.
• ACOD1/itaconate axis is induced by Toll-like receptor signaling and infection, linking metabolism to innate immunity.
• Itaconate suppresses pro-inflammatory cytokine production and ameliorates cytokine storm syndrome.
• ACOD1 deficiency or itaconate treatment alters outcomes in polymicrobial sepsis models.
• Itaconate suppresses atherosclerosis by activating Nrf2-dependent anti-inflammatory responses in macrophages.
• ACOD1-mediated inhibition of aerobic glycolysis suppresses osteoclast differentiation and bone erosion in arthritis.
• Neutrophil ACOD1 promotes breast cancer metastasis by resisting ferroptosis.
• Glucocorticoids promote anti-inflammatory effects partly through metabolic rewiring involving ACOD1.
• Aconitate decarboxylase activity is a potential drug target for inflammatory and metabolic diseases.
• Studying this activity requires integrated CRISPR models and metabolic profiling.
Molecular Mechanism of aconitate decarboxylase activity
Substrate recognition and binding
In simple terms: The enzyme grabs cis-aconitate, a small molecule from the TCA cycle, and holds it in place.
Aconitate decarboxylase activity specifically recognizes cis-aconitate, an intermediate of the tricarboxylic acid (TCA) cycle. The enzyme binds this substrate and positions it for decarboxylation, distinguishing it from other TCA intermediates. This specificity ensures that itaconate is produced only when cis-aconitate is available, linking the activity to mitochondrial metabolic flux.
Catalytic decarboxylation
In simple terms: The enzyme removes a carboxyl group from cis-aconitate, releasing CO2 and leaving itaconate.
The catalytic mechanism of aconitate decarboxylase activity involves the removal of a carboxyl group from cis-aconitate, yielding itaconate and carbon dioxide. This decarboxylation reaction is the committed step in itaconate biosynthesis. The enzyme is classified as a carboxy-lyase, reflecting its ability to cleave a carbon-carbon bond with release of CO2.
Cofactors and metal requirements
In simple terms: The enzyme may need specific helper molecules or metals to work, but details are still being studied.
The exact cofactor requirements for aconitate decarboxylase activity are not fully defined in the provided literature. However, as a decarboxylase, it may rely on conserved active-site residues for catalysis. Further biochemical studies are needed to clarify whether metal ions or coenzymes modulate its activity.
Regulation of enzyme expression
In simple terms: The amount of the enzyme is controlled by immune signals, so itaconate production ramps up during infection.
ACOD1, the gene encoding aconitate decarboxylase activity, is strongly induced by inflammatory stimuli such as lipopolysaccharide and cytokines. This transcriptional induction is a key regulatory layer, ensuring that itaconate is produced during immune activation. Glucocorticoids can also promote metabolic rewiring that involves ACOD1, further linking hormonal signals to this activity.
Downstream effects of itaconate
In simple terms: The itaconate made by this enzyme changes how cells use energy and fight inflammation.
Itaconate produced by aconitate decarboxylase activity inhibits succinate dehydrogenase, leading to altered mitochondrial respiration and increased succinate levels. It also activates Nrf2, an antioxidant transcription factor, and inhibits aerobic glycolysis in certain contexts. These downstream effects mediate the anti-inflammatory and immunomodulatory roles of ACOD1.
Key Genes Involved in GO:0047613 aconitate decarboxylase activity
The following genes and proteins are central to aconitate decarboxylase activity, its regulation, and its biological effects.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ACOD1 (IRG1) | Encodes the enzyme with aconitate decarboxylase activity | Core gene for itaconate production; knockout and overexpression models |
| SDHA/SDHB | Succinate dehydrogenase subunits inhibited by itaconate | Target of itaconate; links to mitochondrial respiration |
| NFE2L2 (Nrf2) | Transcription factor activated by itaconate | Mediates anti-inflammatory effects |
| HIF1A | Hypoxia-inducible factor, affected by itaconate | Links to glycolysis and inflammation |
| IL1B | Pro-inflammatory cytokine suppressed by itaconate | Readout of anti-inflammatory effects |
| TNF | Pro-inflammatory cytokine modulated by itaconate | Inflammation marker |
| IL6 | Cytokine involved in cytokine storm | Itaconate reduces IL6 in cytokine storm models |
| GSDMD | Gasdermin D, involved in pyroptosis | May be modulated by itaconate |
| NLRP3 | Inflammasome component | Itaconate can inhibit NLRP3 inflammasome |
| LDHA | Lactate dehydrogenase A, glycolysis enzyme | Itaconate inhibits aerobic glycolysis |
| PKM | Pyruvate kinase M, glycolysis enzyme | Glycolysis target of itaconate |
| NFKB1 | NF-kB subunit, inflammatory transcription factor | Itaconate modulates NF-kB signaling |
| STAT1 | Transcription factor for inflammatory responses | ACOD1 induction is STAT1-dependent |
| IRF1 | Interferon regulatory factor | Regulates ACOD1 expression |
| GPX4 | Glutathione peroxidase 4, ferroptosis regulator | ACOD1 in neutrophils resists ferroptosis |
| SLC7A11 | Cystine transporter, ferroptosis regulator | Linked to ferroptosis resistance |
| ACSL4 | Acyl-CoA synthetase long-chain family member 4 | Ferroptosis marker |
| FTH1 | Ferritin heavy chain | Iron metabolism in ferroptosis |
How Is aconitate decarboxylase activity Regulated?
Aconitate decarboxylase activity is primarily regulated at the transcriptional level. ACOD1 expression is induced by Toll-like receptor signaling, interferons, and cytokines such as TNF and IL-1beta. Transcription factors including STAT1 and IRF1 contribute to ACOD1 induction. Glucocorticoids can also promote metabolic rewiring that involves ACOD1, suggesting hormonal control. Post-transcriptional and post-translational regulation may exist but are less defined. The activity is also influenced by substrate availability, as cis-aconitate levels depend on TCA cycle flux.
aconitate decarboxylase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ACOD1 | Breast cancer metastasis | ACOD1 knockout in neutrophil-like cells or mouse models |
| ACOD1 | Polymicrobial sepsis | ACOD1 knockout mice with cecal ligation and puncture |
| ACOD1 | Atherosclerosis | ApoE-deficient mice with ACOD1 overexpression or knockout |
| ACOD1 | Arthritis | Collagen-induced arthritis models with ACOD1 modulation |
| ACOD1 | Cytokine storm syndrome | LPS-induced cytokine storm models with ACOD1 knockout |
Aconitate decarboxylase activity in cancer
ACOD1-derived itaconate has been implicated in cancer progression. In breast cancer, neutrophils expressing ACOD1 resist ferroptosis and promote metastasis, suggesting that aconitate decarboxylase activity supports tumor-promoting functions in the tumor microenvironment. This highlights ACOD1 as a potential target in cancer therapy.
Aconitate decarboxylase activity in inflammatory and infectious diseases
Itaconate produced by aconitate decarboxylase activity suppresses inflammation and has antimicrobial effects. In polymicrobial sepsis, ACOD1 is a mediator of disease outcomes, and its deletion or modulation alters survival. Itaconate also ameliorates cytokine storm syndrome by promoting neutrophil-macrophage communication. These findings underscore the therapeutic potential of targeting this activity in sepsis and cytokine storm.
Aconitate decarboxylase activity in atherosclerosis and arthritis
Itaconate suppresses atherosclerosis by activating Nrf2-dependent anti-inflammatory responses in macrophages. In arthritis, ACOD1-mediated inhibition of aerobic glycolysis suppresses osteoclast differentiation and attenuates bone erosion. Thus, aconitate decarboxylase activity plays a protective role in these chronic inflammatory conditions.
Aconitate decarboxylase activity and glucocorticoid action
Glucocorticoids, widely used anti-inflammatory drugs, promote metabolic rewiring that includes ACOD1, contributing to their anti-inflammatory effects. This links aconitate decarboxylase activity to the mechanism of action of a major drug class.
From aconitate decarboxylase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does ACOD1 loss affect itaconate production? | ACOD1 knockout cell lines (e.g., macrophages) |
| Does a specific point mutation alter catalytic activity? | Point-mutation knock-in of ACOD1 |
| Can tagged ACOD1 be used for localization studies? | Knock-in of fluorescent or epitope tag |
| Does ACOD1 overexpression increase itaconate? | Overexpression of ACOD1 in cell lines |
| Which genes mediate itaconate effects? | CRISPR library screening in macrophages |
| Does ACOD1 modulate tumor metastasis? | ACOD1 knockout in cancer models |
How to Study the aconitate decarboxylase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| LC-MS metabolomics | Itaconate and cis-aconitate levels | Quantify enzyme activity |
| RNA-seq | ACOD1 expression and transcriptome changes | Identify regulatory networks |
| Western blot | ACOD1 protein levels | Validate knockout/overexpression |
| CRISPR knockout | Loss of ACOD1 function | Test causality in disease models |
| CRISPR knock-in | Tagged or mutant ACOD1 | Study localization or catalytic residues |
| Flow cytometry | Immune cell phenotypes | Assess itaconate effects on immune cells |
| Seahorse assay | Mitochondrial respiration and glycolysis | Measure metabolic effects of itaconate |
| Bacterial killing assay | Antimicrobial activity | Test itaconate function |
Metabolic profiling
Mass spectrometry-based metabolomics is used to measure itaconate and cis-aconitate levels, directly reflecting aconitate decarboxylase activity. This approach can quantify pathway flux and assess the impact of genetic or pharmacological perturbations.
Transcriptomic analysis
RNA sequencing (RNA-seq) is employed to measure ACOD1 expression and identify downstream transcriptional changes mediated by itaconate. This helps define the regulatory network and inflammatory signatures associated with aconitate decarboxylase activity.
Proteomic and immunoblotting approaches
Western blotting and proteomics can detect ACOD1 protein levels and post-translational modifications. These methods are useful for validating knockout or overexpression models.
Functional assays
Functional assays such as bacterial killing, cytokine production, and ferroptosis sensitivity assess the biological consequences of aconitate decarboxylase activity. These readouts link the enzymatic activity to immune and disease phenotypes.
How CRISPR Can Be Used to Study GO:0047613 aconitate decarboxylase activity
Knockout
CRISPR knockout of ACOD1 eliminates aconitate decarboxylase activity, enabling researchers to test its role in itaconate production and disease phenotypes. For example, ACOD1 knockout in neutrophils or macrophages has been used to demonstrate effects on ferroptosis and sepsis outcomes.
Point Mutation
Point mutations can be introduced into ACOD1 to dissect catalytic residues or regulatory sites, providing insight into the enzymatic mechanism of aconitate decarboxylase activity. Such models help distinguish catalytic activity from other protein functions.
Knock-in
Knock-in of tags or reporters into the ACOD1 locus allows real-time tracking of enzyme expression and localization without altering endogenous regulation. This is valuable for studying aconitate decarboxylase activity in living cells.
Overexpression
Overexpression of ACOD1 increases aconitate decarboxylase activity and itaconate levels, enabling gain-of-function studies in inflammation and cancer models. This approach can reveal sufficiency of the enzyme in driving phenotypes.
How EDITGENE Supports aconitate decarboxylase activity Research
Researchers studying aconitate decarboxylase activity-related genes often need to determine whether a candidate gene is causally involved in itaconate production, immune regulation, or disease progression. EDITGENE provides comprehensive CRISPR cell model services to accelerate this discovery process, from knockout to precise knock-in and library screening.
Contact EDITGENE today to design your custom CRISPR model for aconitate decarboxylase activity research.
Frequently Asked Questions About aconitate decarboxylase activity
What is aconitate decarboxylase activity?
Aconitate decarboxylase activity (GO:0047613) is the enzymatic catalysis of cis-aconitate + H+ = CO2 + itaconate, the key step in itaconate biosynthesis.
What gene encodes aconitate decarboxylase activity?
The enzyme is encoded by ACOD1 (also known as IRG1) in humans and mice.
What is the reaction catalyzed by aconitate decarboxylase?
It converts cis-aconitate and a proton into itaconate and carbon dioxide.
What diseases are associated with aconitate decarboxylase activity?
It is implicated in sepsis, atherosclerosis, arthritis, cytokine storm, and breast cancer metastasis.
How is aconitate decarboxylase activity regulated?
It is primarily regulated by transcriptional induction of ACOD1 via inflammatory signals such as Toll-like receptor activation and cytokines.
What is the role of itaconate in immunity?
Itaconate has anti-inflammatory and antimicrobial effects, inhibiting succinate dehydrogenase and activating Nrf2.
How can I study aconitate decarboxylase activity in the lab?
Common methods include metabolomics to measure itaconate, RNA-seq for ACOD1 expression, and CRISPR knockout or overexpression models.
What CRISPR models are available for ACOD1 research?
Knockout, point mutation, knock-in, and overexpression models can be generated to study ACOD1 function.
Does ACOD1 affect cancer progression?
Yes, ACOD1 in neutrophils promotes breast cancer metastasis by resisting ferroptosis.
What are the synonyms for aconitate decarboxylase activity?
Synonyms include CAD activity, cis-aconitate carboxy-lyase activity, cis-aconitate carboxy-lyase (itaconate-forming), and cis-aconitic decarboxylase activity.
Conclusion
Aconitate decarboxylase activity (GO:0047613) is a central enzymatic function in immunometabolism, responsible for producing itaconate from cis-aconitate. Its roles in inflammation, infection, cancer, and autoimmune conditions make it a compelling target for basic and translational research. By leveraging CRISPR cell models and integrated omics, researchers can dissect the mechanisms and therapeutic potential of this activity.
References
- 1. Zhao Y et al.. 2023. Neutrophils resist ferroptosis and promote breast cancer metastasis through aconitate decarboxylase 1.. Cell Metab 35(10):1688-1703.e10 PMID: 37793345
- 2. Peace CG et al.. 2022. The role of itaconate in host defense and inflammation.. J Clin Invest 132(2) PMID: 35040439
- 3. Wu R et al.. 2020. ACOD1 in immunometabolism and disease.. Cell Mol Immunol 17(8):822-833 PMID: 32601305
- 4. Auger JP et al.. 2024. Metabolic rewiring promotes anti-inflammatory effects of glucocorticoids.. Nature 629(8010):184-192 PMID: 38600378
- 5. Kang H et al.. 2024. Neutrophil-macrophage communication via extracellular vesicle transfer promotes itaconate accumulation and ameliorates cytokine storm syndrome.. Cell Mol Immunol 21(7):689-706 PMID: 38745069
- 6. Song J et al.. 2023. Itaconate suppresses atherosclerosis by activating a Nrf2-dependent antiinflammatory response in macrophages in mice.. J Clin Invest 134(3) PMID: 38085578
- 7. Wu R et al.. 2022. Aconitate decarboxylase 1 is a mediator of polymicrobial sepsis.. Sci Transl Med 14(659):eabo2028 PMID: 36001682
- 8. Kachler K et al.. 2024. Acod1-mediated inhibition of aerobic glycolysis suppresses osteoclast differentiation and attenuates bone erosion in arthritis.. Ann Rheum Dis 83(12):1691-1706 PMID: 38964754
